ABSTRACT
One of the simplest ways of creating vacuum is to lower the temperature of a gas until it condenses into a liquid or becomes a solid. There are, however, two practical difficulties in using this concept. In industrial practice, instead of cooling the entire chamber it is sufficient to introduce in the chamber a cold surface that will condense the gas. Also, instead of relying on condensation alone, special porous materials are used to provide a large surface area to adsorb the gas more efficiently. Cryosorption pumps are not continuous throughput pumps. The pumped gas is not exhausted to the atmosphere, but kept inside the pump. The gas remains in the pump either as a thin film having a density of the liquid, or as a deposit resembling snow or frost. A compressor is required as part of the cryogeneration system to circulate helium through the expander assembly and to recompress it.
